The evolving technologies for assessing gene expression on DNA microarrays shift the scale of study from single genes to whole genomes and provide opportunities to globally examine the alterations in gene expression that occur following different drug treatments. This exploratory grant application aims to adapt gene microarray approaches to assess the adaptive changes in gene expression that take place after psychostimulant drug administration. The biogenic amine carriers have long been recognized as the primary targets for psychostimulant drugs of abuse, as well as anti-depressants, and drugs used to treat attention deficit hyperactivity disorder (ADHD). However, we know relatively little about how inhibition of transport by drugs with varying selectivities leads to such striking yet diverse behavioral consequences. The proposed studies use rat gene chip arrays to examine the impact of cocaine and eventually other monoamine transport inhibitors on gene expression profiles in key brain regions. A second aim of the proposal will examine differences in the profiles of gene expression in animals trained to self-administer cocaine. Rather than developing the DNA arrays for ourselves (a task we prefer to leave to engineers), we have chosen state-of-the-art, commercially available arrays obtained from Affymetrix/TM as the most efficient and reliable method for analyzing the expression of 10/4-10/5 different genes in parallel. The system uses microarrays of gene-specific oligonucleotides synthesized on a glass substrate which are hybridized with biotinylated probes representing the sequences expressed in the tissues of interest. Comparisons expression profiles will be accomplishes using a suite of programs available for the analysis of gene chip data. Changes in expression observed on microarrays will be confirmed using conventional approaches including Northern blotting analyses and in situ hybridization. A final aim will compare global changes in the expression profiles obtained using different classes of transport inhibitors. This latter study will assess the utility of array technology in determining "signature" gene expression profiles for different classes of drugs that act on related targets. Understanding the common and unique actions of drugs from a global, genomic perspective should enable us to characterize and understand the mechanisms that underlie their profound behavioral consequences.